Content-protected digital link over a single signal line

ABSTRACT

A packet based high bandwidth copy protection method is described that includes the following operations. Forming a number of data packets at a source device, encrypting selected ones of the data packets based upon a set of encryption values, transmitting the encrypted data packets from the source device to a sink device coupled thereto, decrypting the encrypted data packets based in part upon the encryption values, and accessing the decrypted data packets by the sink device.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation-in-part of U.S. patentapplication Ser. No. 10/762,680 filed Jan. 21, 2004 entitled “PACKETBASED HIGH DEFINITION HIGH-BANDWIDTH DIGITAL CONTENT PROTECTION” byKobayashi that, in turn, takes priority under 35 U.S.C. 119(e) to U.S.Provisional Patent Application No. 60/506,193 filed Sep. 26, 2003entitled “PROVIDING HIGH DEFINITION COPY PROTECTION IN A PACKET BASEDDATA STREAM” by Kobayashi, each of which is incorporated by reference inits entirety for all purposes. This application is also related to (i)U.S. patent application Ser. No. 10/726,794 filed Dec. 2, 2003 entitled“PACKET BASED VIDEO DISPLAY INTERFACE AND METHODS OF USE THEREOF” byKobayashi that, in turn, takes priority under 35 U.S.C. 119(e) to (ii)U.S. Provisional Patent Application No. 60/467,804 filed May 1, 2003entitled “DIGITAL/ANALOG VIDEO INTERCONNECT AND METHODS OF USE THEREOF”by Kobayashi, (iii) U.S. Provisional Patent Application No. 60/504,060filed Sep. 18, 2003 entitled “DIGITAL/ANALOG VIDEO INTERCONNECT ANDMETHODS OF USE THEREOF” by Kobayashi, (iv) U.S. Provisional PatentApplication No. 60/474,085 filed May 28, 2003 entitled “DIGITAL/ANALOGVIDEO INTERCONNECT AND METHODS OF USE THEREOF” by Kobayashi, and (v)U.S. Provisional Patent Application No. 60/474,084 filed May 28, 2003entitled “SIMPLE ENUMERATION METHOD FOR THE LINK CLOCK RATE AND THEPIXEL/AUDIO CLOCK RATE” by Kobayashi, each of which is herebyincorporated by reference herein in their entirety. This application isalso related to the following U.S. patent applications each of which isherein incorporated by reference, (i) U.S. patent application Ser. No.10/726,802 entitled “METHOD OF ADAPTIVELY CONNECTING A VIDEO SOURCE ANDA VIDEO DISPLAY” by Kobayashi; (ii) U.S. patent application Ser. No.10/726,438 that issued as U.S. Pat. No. 7,068,686 and continuing U.S.patent application Ser. No. 11/291,015 that issued as U.S. Pat. No.7,177,329, both entitled “METHOD AND APPARATUS FOR EFFICIENTTRANSMISSION OF MULTIMEDIA DATA PACKETS” by Kobayashi; (iii) U.S. patentapplication Ser. No. 10/726,440 entitled “METHOD OF OPTIMIZINGMULTIMEDIA PACKET TRANSMISSION RATE” by Kobayashi; (iv) U.S. patentapplication Ser. No. 10/727,131 entitled “USING AN AUXILIARY CHANNEL FORVIDEO MONITOR TRAINING” that issued as U.S. Pat. No. 7,088,741 byKobayashi; (v) U.S. patent application Ser. No. 10/726,350 entitled“TECHNIQUES FOR REDUCING MULTIMEDIA DATA PACKET OVERHEAD” by Kobayashi;(vi) U.S. patent application Ser. No. 10/726,362 entitled “PACKET BASEDCLOSED LOOP VIDEO DISPLAY INTERFACE WITH PERIODIC STATUS CHECKS” byKobayashi; (vii) U.S. patent application Ser. No. 10/726,895 entitled“MINIMIZING BUFFER REQUIREMENTS IN A DIGITAL VIDEO SYSTEM” by Kobayashi;and (viii) U.S. patent application Ser. No. 10/726,441 entitled “VIDEOINTERFACE ARRANGED TO PROVIDE PIXEL DATA INDEPENDENT OF A LINK CHARACTERCLOCK” by Kobayashi; and (ix) U.S. patent application Ser. No.10/726,934 entitled “ENUMERATION METHOD FOR THE LINK CLOCK RATE AND THEPIXEL/AUDIO CLOCK RATE” by Kobayashi that issued as U.S. Pat. No.6,992,987. This application is also related to the following co-pendingapplications: (x) U.S. patent application Ser. No. 10/909,103 filed Jul.29, 2004 entitled “USING PACKET TRANSFER FOR DRIVING LCD PANEL DRIVERELECTRONICS” by Kobayashi; (xi) U.S. patent application Ser. No.10/909,027 filed Jul. 29, 2004 entitled “BYPASSING PIXEL CLOCKGENERATION AND CRTC CIRCUITS IN A GRAPHICS CONTROLLER CHIP” byKobayashi, and (xi) U.S. patent application Ser. No. 10/909,085 filedJul. 29, 2004 entitled “PACKET BASED STREAM TRANSPORT SCHEDULER ANDMETHODS OF USE THEREOF” by Kobayashi, each of which is incorporated byreference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to display devices. More specifically, theinvention describes a method and apparatus capable of providing a robustencryption of a audio/video data in a packet based transmissionenvironment.

2. Overview

Protection of proprietary digital content has become an importantconsideration and more particularly, in high definition (HD),high-bandwidth applications. Especially important for HD, high-bandwidthapplications, content protection provides assurances that owners ofdigitized content are protected from unauthorized use and copying oftheir proprietary content. A popular high-bandwidth digital-contentprotection scheme developed by Intel Corporation of Santa Clara Calif.commonly referred to as HDCP has been widely implemented. As currentlyconfigured, this particular HDCP protocol is specifically designed foruse in Digital Visual Interface (DVI) and High-Definition MultimediaInterface (HDMI) based environments.

In general, HDCP encrypts the transmission of digital content betweenthe video source, or transmitter—such as a PC, DVD player or set-topbox—and the digital display, or receiver—such as a monitor, televisionor projector. In this way, HDCP is designed to prevent copying orrecording of digital content thereby protecting the integrity of contentas it is being transmitted. For example, as required by the describedHDCP protocol, during an authentication phase, the receiver will only beprovided with content once it demonstrates knowledge of theauthentication keys which the transceiver verifies through computationof a secret value. Furthermore, to prevent eavesdropping and stealing ofthe data, the transmitter and receiver will generate a shared secretvalue that is consistently checked throughout the transmission. Onceauthentication is established, the transmitter encrypts the data andsends it to the receiver for decryption.

The current implementation of the DVI standard requires the use of a setof defined characters based upon a 10 bit transmission protocol. Forexample, as currently configured, only 460 characters (out of a possible1024 available) are used by the receiver for data while 4 characters areused as explicit control signals such as hsync and vsync. In thisarrangement, any time the receiver receives and recognizes one of thepredefined characters representing data, then the received implicitlydefines a data enable signal (DE) as being active thereby indicatingthat the received data is true data. However, whenever one of the 4control characters is received by the receiver, then an implicitassumption is made that data enable (DE) is inactive.

HDCP protocol uses the status of DE, H_(sync), V_(sync) and anothercontrol signal, called CNTL3, to advance its state machine. The DE,H_(sync), and V_(sync) signals are timing signals associated with rastervideo transmitted in a “streaming” manner. In a streaming transfer, thepixel data is transferred at pixel rate and the ratio of blanking periodto data period is preserved. In case of a packet transfer, these timingsignals may not be present. Only the pixel data may be transferred inthe packet stream, while timing information is communicated in adifferent way.

It would be advantageous from a commercial cost standpoint to be able tosupport HDCP protocol over cheaper type cables such as coax cable, cat 5cable, and so on. Unfortunately, however, in order to properly implementthe HDCP protocol, a sideband handshake is required in order to at leastsynchronize the source and the sink devices which in conventionalarrangements would require at least two separate data lines. In thisway, coax cable, cat 5 cable and the like is unsuitable for implementingthe HDCP protocol in a conventional manner.

Therefore, what is required is a way to support high-definition copyprotection that is compatible with existing high definition copyprotection protocols such as HDCP over single cable, such as coax cable.

SUMMARY OF THE INVENTION

What is provided, therefore, is a packet-based digital transmissionmedium and protocol that supports high definition copy protection thatis backwards compatible with existing high definition copy protectionprotocols such as HDCP that can be implemented over a single line cablesuch as co-ax cable or CAT-5 cable. In one embodiment of the invention,a packet based high bandwidth copy protection method is described thatincludes the following operations. Connecting a multimedia source deviceand a multimedia sink device by way of a single line cable;synchronizing the multimedia source device and the multimedia sinkdevice over the single line cable; configuring the single line cable asa main link by the multimedia source device; and passing an HDCPencrypted audio/video (A/V) data stream from the multimedia sourcedevice to the multimedia sink device by way of the single line cable.

In another embodiment, a system for providing high bandwidth copyprotection in a packet based system over a single line cable. The systemincludes, at least, a source unit arranged to provide a number of datapackets having a hot plug detect (HPD) input node connected to thesingle line cable by way of a source side bypass line, and a sink unitcoupled to the source unit arranged to receive the data packets from thesource unit over the single line cable, wherein the source unit and thesink unit are AC coupled by way of a source side coupling capacitor anda sink side coupling capacitor, and wherein the sink unit includes anHPD output node connected to the single line cable by way of a sink sidebypass line, wherein the source side bypass line and the sink sidebypass line provide a DC signal path between the sink device and thesource device, wherein the sink device sets a hot plug detect (HPD)signal to a HPD HI value when the source device and the sink device arenot in synch that is communicated to the source device over the singleline cable configured as an auxiliary channel by the source device andwherein, when the source and the sink device are in sync, the sinkdevice sets the HPD signal to HPD LO and the source device responds byconfiguring the single line cable as a main link and sending anencrypted audio/video data stream over the single line cable to the sinkdevice.

In yet another embodiment, computer program product for providing apacket based high bandwidth copy protection is disclosed that includes,at least, computer code for connecting a multimedia source device and amultimedia sink device by way of a single line cable; computer code forsetting a hot plug detect (HPD) signal to a HPD HI value by themultimedia sink device; computer code for passing the HPD HI signal fromthe multimedia sink device to the multimedia source device; computercode for configuring the single line cable as an auxiliary cable by themultimedia source device in response to the HPD HI signal; computer codefor synchronizing the multimedia source device and the multimedia sinkdevice; computer code for setting the HPD signal to an HPD LO signal bythe multimedia sink device after the multimedia source device and themultimedia sink device are synchronized; computer code for configuringthe single line cable as a main link by the multimedia source device;computer code for passing an audio/video data stream from the multimediasource device to the multimedia sink device by way of the single linecable; and computer readable medium for storing the computer code.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a generalized representation of a cross platform packetbased digital video display interface suitable for use with anyembodiment of the invention.

FIG. 2 shows an encryption system for encrypting audio/video contentsuitable for use with the system described with respect to FIG. 1.

FIG. 3 shows a representative encrypted data stream in accordance withan embodiment of the invention.

FIG. 4 illustrates a system employed to implement the invention.

FIG. 5 illustrates a system in accordance with another embodiment of theinvention.

FIGS. 6A-6B illustrate a flowchart detailing a process in accordancewith an embodiment of the invention.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

Reference will now be made in detail to a particular embodiment of theinvention an example of which is illustrated in the accompanyingdrawings. While the invention will be described in conjunction with theparticular embodiment, it will be understood that it is not intended tolimit the invention to the described embodiment. To the contrary, it isintended to cover alternatives, modifications, and equivalents as may beincluded within the spirit and scope of the invention as defined by theappended claims.

As currently implemented, HDCP establishes a secure channel in order toverify that the display device is licensed to receive protected contentand once established, encrypts the data at the host side and decrypts atthe display device in order to prevent ‘eavesdropping’ of the protectedcontent. In addition, in order to identify unauthorized or compriseddevices, HDCP relies upon authentication and key exchange, contentencryption, and device renewability.

More specifically, HDCP protects copyrighted digital entertainmentcontent in a Digital Video Interface (DVI) environment by encrypting itstransmission between the video source and the digital display(receiver). The video source might be a PC, set-top boxes, DVD playersand the like), and the digital display might be an liquid crystaldisplay (LCD), television, plasma panel, or projector in which allauthorized devices are given a set of unique secret device keys. Duringan authentication process, the receiver must demonstrate its knowledgeof a number of secret device keys before the protected content is sent.After the receiver acknowledges the keys, both devices (the sender andreceiver) generate a shared secret value that is designed to preventeavesdroppers from stealing the content. After authentication, thecontent is encrypted and sent to the receiver that in turn decrypts it.

Authentication is a cryptographic process for verifying that the displaydevice is authorized (or licensed) to receive protected content. Boththe authorized host and the display device have knowledge of a set ofsecret keys that consist of an array of forty 56-bit secret device keysand a corresponding 40-bit binary Key Selection Vector (KSV). The hostinitiates authentication by sending an initiation message containing itsKey Selection Vector, AKSV, and a 64-bit value An. The display deviceresponds by sending a response message containing its Key SelectionVector, BKSV. The host confirms that the received KSV has not beenrevoked. At this point, the two devices can calculate a shared value,which, if both devices have a valid set of keys, will be equal. Thisshared value will be used in the encryption and decryption of theprotected content since authentication has now been established.

The present invention provides for high definition high bandwidth copyprotection over a single line cable, such as coax cable. In oneembodiment of the invention, a source and sink each of which are HotPlug Detect (HPD) capable are AC coupled by way of a single line cable,such as coax cable. When the sink device has determined that the sourcedevice is connected thereto, the sink device sets an HPD signal to anHPD HI value. In response to the HPD signal being set to HI, the sourcedevice initiates a synchronization process with the sink device byconfiguring the single line cable as an auxiliary channel and requestingsynchronization information from the sink device. The sink deviceresponds to the source device request by forwarding appropriatesynchronization information (such as EDID information, and HDCPauthentication information) over the single line cable (configured toact as an auxiliary, or side band, channel). If all information providedby the sink device is deemed appropriate by the sink device, the sinkdevice re-sets the HPD signal to LO and the source device responds byconfiguring the single line cable as a main link and proceeds totransfer an audio/video (A/V) data stream over the single line cable tothe sink device. If at any time the sink device determines that thesynchronization has failed, then the sink device re-sets the HPD signalto HI and is then forwarded to the source device. In response to the HPDsignal being set HI, the source device halts the transmission of the A/Vdata stream and the sink device initiates re-synchronization with thesource device.

A particularly well suited packet based transmission system is describedwith reference to FIG. 1 that shows a generalized representation of across platform packet based digital video display interface 100 suitablefor use with any embodiment of the invention. The interface 100 connectsa transmitter 102 to a receiver 104 by way of a physical link 106 (alsoreferred to as a pipe). In the described embodiment, a number of datastreams 108-112 are received at the transmitter 102 that, if necessary,packetizes each into a corresponding number of data packets 114. Thesedata packets are then formed into corresponding data streams each ofwhich are passed by way of an associated virtual pipe 116-120 to thereceiver 104. It should be noted that the data streams 108-112 can takeany number of forms such as video, graphic, audio, etc.

Typically, when the source is a video source, the data streams 108-112include various video signals that can have any number and type ofwell-known formats, such as composite video, serial digital, paralleldigital, RGB, or consumer digital video. The video signal can be ananalog video signal provided the source 102 includes some form of ananalog video source such as for example, an analog television, stillcamera, analog VCR, DVD player, camcorder, laser disk player, TV tuner,set top box (with satellite DSS or cable signal) and the like. Thesource 102 can also include a digital image source such as for example adigital television (DTV), digital still camera, and the like. Thedigital video signal can be any number and type of well known digitalformats such as, SMPTE 274M-1995 (1920×1080 resolution, progressive orinterlaced scan), SMPTE 296M-1997 (1280×720 resolution, progressivescan), as well as standard 480 progressive scan video.

In the case where the source 102 provides an analog image signal, ananalog-to-digital converter (A/D) converts an analog voltage or currentsignal into a discrete series of digitally encoded numbers (signal)forming in the process an appropriate digital image data word suitablefor digital processing. Any of a wide variety of A/D converters can beused. By way of example, other A/D converters include, for example thosemanufactured by: Philips, Texas Instrument, Analog Devices, Brooktree,and others.

For example, if the data stream 110 is an analog type signal, the ananalog to digital converter (not shown) included in or coupled to thetransmitter 102 will digitize the analog data which is then packetize bya packetizer that converts the digitized data stream 110 into a numberof data packets 114 each of which will be transmitted to the receiver104 by way of the virtual link 116. The receiver 104 will thenreconstitute the data stream 110 by appropriately recombining the datapackets 114 into their original format. It is these data streams thatare ultimately encrypted for form a set of copy protected data streams.

FIG. 2 shows an encryption system 200 for encrypting audio/video contentsuitable for use with the system 100 described with respect to FIG. 1.As shown in FIG. 2, a video source 202 is arranged to provide a numberof data streams such as the data streams 110 and 112. By utilizing anumber of data streams, the system 200 is capable of transmitting videodata, for example, consistent with any of a number of video formatsconcurrently. For example, the data stream 110 is formed of video dataconsistent with 1024×768 at 60 Hz whereas the data stream 112 is formedof video data consistent with 640×480 at 75 Hz, and so on. In order fora receiver 204 (such as a monitor) to reconstruct the video in theappropriate format, the data streams include in addition the appropriatevideo data associated attribute data that is used by the receiver toreconstruct the video in the appropriate format.

Accordingly, the video source 202 includes a number of buffers 206 eachof which is used to buffer an associated one of the video data streams.Each of the buffers is, in turn, coupled to a multiplexer 208 that isused to select a particular one of the data streams for transmission toa packetizer 210. The packetizer 210 parses the incident data streaminto an associated number of data packets by incorporating a packet ID,optionally performing error correction, and attaching a time stamp andany of the attributes deemed important or necessary for the correctreconstruction of the video raster by the receiver 404. An encryptioncontrol generator unit 212 applies an appropriate encryption algorithmto each of the data packets based at least by inserting a control packetthat conveys signals such as H_(sync), V_(sync), and a particularcontrol character CNTL3 used to flag those data packets that areencrypted (and conversely those data packets that are not encrypted).

In accordance with an embodiment of the invention, the resultingencrypted data stream 214 (a particular example of which is shown inFIG. 3 as a data stream 300) is formed of a number of data packets. Thedata stream 300 includes a number of control packets 302 used to markthose video data packets that are encrypted (or not encrypted) as thecase may be. Each video packet has an associated header 304 thatincludes, in part, the attribute data described above associated withthe video data packet 306. For example, in the case shown in FIG. 3, thedata stream 300 includes data packets for the data stream 110 and thedata stream 112 conjoined into the data stream 300 such that the trafficbetween the video source 202 and the receiver 204 is consistent with aconstant link environment.

It should be noted that in the described embodiment, the data stream 300is time domain multiplexed, those data packets associated with the datastream 110 have a longer duration than those associated with the datastream 112. In these cases, a time-base recovery (TBR) unit 216 withinthe receiver 204 regenerates the stream's original native rate usingtime stamps embedded in the main link data packets, if necessary.Referring back to FIG. 2, at the receiver 404, a deserializer unit 218receives the encrypted data stream 300 that provides input to a decoderunit 220 and a depacketizer 222. The decoder 220 decodes the controlpacket, thus feeding H_(sync), V_(sync), and a particular controlcharacter CNTL3 provided to a decryption engine 228 that was previouslyused to for encryption.

FIG. 4 illustrates a system 400 employed to implement the invention.Computer system 400 is only an example of a graphics system in which thepresent invention can be implemented. System 400 includes centralprocessing unit (CPU) 410, random access memory (RAM) 420, read onlymemory (ROM) 425, one or more peripherals 430, graphics controller 460,primary storage devices 440 and 450, and digital display unit 470. CPUs410 are also coupled to one or more input/output devices 490 that mayinclude, but are not limited to, devices such as, track balls, mice,keyboards, microphones, touch-sensitive displays, transducer cardreaders, magnetic or paper tape readers, tablets, styluses, voice orhandwriting recognizers, or other well-known input devices such as, ofcourse, other computers. Graphics controller 460 generates analog imagedata and a corresponding reference signal, and provides both to digitaldisplay unit 470. The analog image data can be generated, for example,based on pixel data received from CPU 410 or from an external encode(not shown). In one embodiment, the analog image data is provided in RGBformat and the reference signal includes the V_(SYNC) and H_(SYNC)signals well known in the art. However, it should be understood that thepresent invention can be implemented with analog image, data and/orreference signals in other formats. For example, analog image data caninclude video signal data also with a corresponding time referencesignal.

FIG. 5 illustrates a system 600 in accordance with another embodiment ofthe invention. System 600 includes multimedia source device 602 ACcoupled to multimedia sink device 604 by way of single line cable 606(such as co-ax cable) that can take the form of a single differentialpair. Source device 602 includes main link transmitter (TX) 608 arrangedto transmit audio-video (AV) stream 610 over uni-directional main link606. Auxiliary channel transceiver (AUX CH TRX) 612 transmits and/orreceives side-band signal SB (such as control packets) overbi-directional auxiliary channel 614. Hot plug detect (HPD) monitor 616monitors whether or not sink device 604 is present. When sink device 604is present, HPD driver 618 sets HPD signal 620 to a high level,otherwise HPD driver 618 sets HPD signal 620 to a low level. In thedescribed embodiment, sink device 604 includes main link receiver (RX)622 arranged to receive AV stream stream 610 and auxiliary channeltransceiver (AUX CH TRX) 624.

Since source device 602 and sink device 604 are AC coupled, couplingcapacitors 626 and 628 are used to connect source device 602 and sinkdevice 604 such that only AC signals can pass while any DC signal isblocked. Therefore, by providing a source side Hot Plug Detect (HPD)bypass line 630 from node A to HPD monitor 616 at source device 602 anda sink side HPD bypass line 632 connecting point B to HPD driver 618 atsink device 604, any HPD signal (that is a DC signal) from source device602 to sink device 604 is blocked by coupling capacitors 626 and 628from reaching either the source device 602 except by the HPD monitor616. Therefore any DC signal that passes between multimedia sourcedevice 602 and multimedia sink device 604 is blocked by couplingcapacitors 626 and 628. In this way, the status of the HPD signal 620(either high or low) does not affect the main link transport and/or AUXCH transactions.

FIGS. 6A and 6B show a flowchart detailing a process 900 in accordancewith an embodiment of the invention. The process 900 begins at 902 bymonitoring the HPD signal. When at 902 the HPD signal is LOW, then boththe source and the sink are in OFF state at 904, however, when it isdetected at 906 that the HPD signal is going from low to high, thesource device enables AUX CH TRX and disables Main Link TX at 908 andthe sink device enables AUX CH TRX while disabling Main Link RX(referred to as “SETUP” state) at 910. In the SETUP mode, the followingAUX CH transactions take place, at 912, EDID read to understand the sinkdevice capability (e.g., display resolution, color depth, audiocapability), at 914 DPCD read to understand the Main Link RX capability(e.g. supported link rate) and at 916 authentication for contentprotection in order to validate the sink device where authenticationtakes place last. Once the authentication is completed at 918, controlis passed to 920 shown in FIG. 6B where the Source Device disables theAUX CH TRX and enables the main link TX at 920 and the Sink Devicedisables the AUX CH TRX and enables Main Link TX and RX at 922 (thisstate is called “STREAM TRANSPORT”). In the STREAM TRANSPORT state, theSink Device verifies the CP synchronization between Source and Sink at924. In the described embodiment, the verification is performed the sinkdevice verifying a validity of “CP synch bit” transported as part of theAV stream. During the STREAM TRANSPORT state, an AV data stream is sentfrom the source to the sink at 926 until at 928 the AV stream iscomplete at which point process 700 stops, otherwise at 930 if and whenthe CP synch is lost or whenever the Sink Device gets out of STREAMTRANSPORT state at 932, the HPD signal goes low at 934, notifying theSource Device of this state change. If on the other hand, neither CPsync is lost or sink device is out of STREAM TRANSPORT mode, thencontrol is passed back to 926.

Upon HPD turning low at 934, both the Source and Sink Devices go to OFFstate at 936. When the HPD signal is driven HIGH by the Sink Device at938, the Source and Sink Devices return to SETUP mode at 904. Using thismethod, a content-protected AV stream (or streams) can be transportedover a single signal line.

Although only a few embodiments of the present invention have beendescribed, it should be understood that the present invention may beembodied in many other specific forms without departing from the spiritor the scope of the present invention. The present examples are to beconsidered as illustrative and not restrictive, and the invention is notto be limited to the details given herein, but may be modified withinthe scope of the appended claims along with their full scope ofequivalents.

While this invention has been described in terms of a preferredembodiment, there are alterations, permutations, and equivalents thatfall within the scope of this invention. It should also be noted thatthere are many alternative ways of implementing both the process andapparatus of the present invention. It is therefore intended that theinvention be interpreted as including all such alterations,permutations, and equivalents as fall within the true spirit and scopeof the present invention.

1. A packet based high bandwidth copy protection (HDCP) methodcomprising: connecting a multimedia source device and a multimedia sinkdevice by way of a single line cable; setting a hot plug detect (HPD)signal to a HPD HI value by the multimedia sink device; passing the HPDHI signal from the multimedia sink device to the multimedia sourcedevice; configuring the single line cable as an auxiliary channel by themultimedia source device in response to the HPD HI signal; synchronizingthe multimedia source device and the multimedia sink device; setting theHPD signal to an HPD LO signal by the multimedia sink; configuring thesingle line cable as a main link by the multimedia source device afterthe source device and the sink device are synchronized; forming an HDCPencrypted audio/video (A/V) data stream by: encrypting selected datapackets; generating a control packet at the source device used foridentifying the selected encrypted data packets; and combining at leastthe control packet and the identified encrypted data packets; passingthe HDCP encrypted audio/video (A/V) data stream from the multimediasource device to the multimedia sink device by way of the single linecable; and decrypting only those packets identified by the controlpacket.
 2. A method as recited in claim 1, wherein the synchronizingcomprises: setting a hot plug detect (HPD) signal to a HPD HI value bythe multimedia sink device; passing the HPD HI signal from themultimedia sink device to the multimedia source device; configuring thesingle line cable as an auxiliary channel by the multimedia sourcedevice in response to the HPD HI signal; and passing synchronizationinformation between the multi-media source device and the multimediasink device by way of the single line cable as the auxiliary channel. 3.A method as recited in claim 2, further comprising: setting the HPDsignal to an HPD LO signal by the multimedia sink device after themultimedia source device and the multimedia sink device aresynchronized.
 4. A method as recited in claim 1, further comprising: ifthe source device and the sink device fall out of synchronization,setting the HPD signal to HPD HI by the sink device; halting the A/Vdata stream by the source device; configuring the single line cable tothe auxiliary channel by the source device in response to HPD HI; andre-synchronizing the source device and the sink device.
 5. A method asrecited in claim 1, further comprising: forming a number of data packetsat the source device; encrypting the data packets based upon a set ofencryption values; transmitting the encrypted data packets from thesource device to a sink device coupled thereto as the A/V data stream;decrypting the encrypted data packets based in part upon the encryptionvalues; and accessing the decrypted data packets by the sink device. 6.A method as recited in claim 5, wherein the source device is a videosource and wherein the sink device is a video display and wherein thenumber of data packets include some audio data packets and some videodata packets.
 7. A method as recited in claim 6, wherein theencryption/decryption control signals include a Vsync, an Hsync, and aCNTL3.
 8. A method as recited in claim 7, wherein each of the datapackets is identified by associated with a particular control packet asbeing either encrypted or not encrypted.
 9. A method as recited in claim8, wherein when the CNTL3 is active, then the corresponding data packetis encrypted and vice-versa.
 10. A method as recited in claim 1, whereinthe single line cable is a co-ax cable.
 11. A method as recited in claim10, wherein the single line cable is a CAT-5 cable.
 12. A system forproviding high bandwidth copy protection in a packet based system over acable having only a single line, comprising: a source unit arranged toprovide a number of data packets having a hot plug detect (HPD) inputnode connected to the single line cable by way of a source side bypassline; and a sink unit coupled to the source unit arranged to receive thedata packets from the source unit over the single line cable, whereinthe source unit and the sink unit are AC coupled by way of a source sidecoupling capacitor and a sink side coupling capacitor, and wherein thesink unit includes an HPD output node connected to the single wire cableby way of a sink side bypass line, wherein the source side bypass lineand the sink side bypass line provide a DC signal path between the sinkdevice and the source device, wherein the sink device sets a hot plugdetect (HPD) signal to a HPD HI value when the source device and thesink device are not in synch that is communicated to the source deviceover the single wire cable configured as an auxiliary channel by thesource device and wherein, when the source and the sink device are insync, the sink device sets the HPD signal to HPD LO and the sourcedevice responds by configuring the single line cable as a main link,forming an HDCP encrypted audio/video (A/V) data stream by encryptingselected data packets, generating a control packet at the source deviceused for identifying the selected encrypted data packets, and combiningat least the control packet and the identified encrypted data packets,and sending an encrypted audio/video data stream over the single linecable to the sink device.
 13. A system as recited in claim 12, furthercomprising: an encryption unit coupled to the source unit arranged toencrypt selected ones of the data packets sent from the source unit tothe sink unit; a decryption unit coupled to the sink unit arranged todecrypt the encrypted data packets; and an encryption/decryption valuesgenerator arranged to provide a set of encryption/decryption values usedto encrypt and decrypt the appropriate data packets.
 14. A system asrecited in claim 13, wherein the source unit is an audio/video unitarranged to provide audio type data packets and/or video type datapackets.
 15. A system as recited in claim 14, wherein the sink unit is adisplay unit arranged to display processed ones of the video datapackets.
 16. A system as recited in claim 15, wherein the display unitincludes a number of speakers arranged to transmit audio signals basedupon processed ones of the audio data packets.
 17. A system as recitedin claim 16, wherein the set of encryption/decryption control signalsinclude Vsynch, Hsynch corresponding to the video data packets.
 18. Asystem as recited in claim 17, wherein the set of encryption/decryptioncontrol signal further includes CNTL3 to flag those data packets thatare encrypted.
 19. Computer program product executable by a processor,comprising: computer code for connecting a multimedia source device anda multimedia sink device by way of a single line cable; computer codefor setting a hot plug detect (HPD) signal to a HPD HI value by themultimedia sink device; computer code for passing the HPD HI signal fromthe multimedia sink device to the multimedia source device; computercode for configuring the single line cable as an auxiliary cable by themultimedia source device in response to the HPD HI signal; computer codefor synchronizing the multimedia source device and the multimedia sinkdevice; computer code for setting the HPD signal to an HPD LO signal bythe multimedia sink device after the multimedia source device and themultimedia sink device are synchronized; computer code for configuringthe single line cable as a main link by the multimedia source deviceafter the source device and the sink device are synchronized; andcomputer code for forming an HDCP encrypted audio/video (A/V) datastream by: encrypting selected data packets; generating a control packetat the source device used for identifying the selected encrypted datapackets; and combining at least the control packet and the identifiedencrypted data packets; decrypting only those packets identified by thecontrol packet; computer code for passing the audio/video data streamfrom the multimedia source device to the multimedia sink device by wayof the single line cable; computer code for decrypting only thosepackets identified by the control packet; and computer readable mediumfor storing the computer code.
 20. Computer program product as recitedin claim 19, further comprising: computer code for determining if thesource device and the sink device fall out of synchronization, computercode for setting the HPD signal to HPD HI by the sink device; computercode for halting the A/V data stream by the source device; computer codefor configuring the single wire cable to the auxiliary channel by thesource device in response to HPD HI; and computer code forre-synchronizing the source device and the sink device.
 21. A Computerchip configured to: set a hot plug detect (HPD) signal to a HPD HI; passthe HPD HI signal to a multimedia source device; configure a single linecable connecting the multimedia source device and a multimedia sink asan auxiliary channel in response to the HPD HI signal; synchronize themultimedia source device and the multimedia sink device; set the HPDsignal to an HPD LO signal by the multimedia sink; configure the singleline cable as a main link by the multimedia source device after thesource device and the sink device are synchronized; form an HDCPencrypted audio/video (A/V) data stream by: encrypting selected datapackets; generating a control packet at the source device used foridentifying the selected encrypted data packets; and combining at leastthe control packet and the identified encrypted data packets; pass theHDCP encrypted audio/video (A/V) data stream from the multimedia sourcedevice to the multimedia sink device by way of the single line cable;and decrypting only those packets identified by the control packet. 22.A method as recited in claim 1, wherein the configuring the single linecable as an auxiliary channel includes enabling an auxiliary channeltransceiver and disabling a main link transmitter, wherein thesynchronizing includes utilizing the auxiliary channel transceiver, andwherein the configuring the single line cable as a main link includesdisabling the auxiliary channel transceiver and enabling a main linktransmitter, wherein the auxiliary channel transceiver transmits and/orreceives side-band signals over a bi-directional channel and wherein themain link transmitter transmits information over a uni-directional link.23. A system as recited in claim 12, wherein the source unit includes anauxiliary channel transceiver and main link transmitter, wherein thesink unit includes an auxiliary channel transceiver and main linkreceiver, and wherein the source device responds to the HPD LO signal bydisabling the auxiliary channel transceiver and enabling the main linktransmitter, wherein the auxiliary channel transceiver transmits and/orreceives side-band signals over a bi-directional channel and wherein themain link transmitter transmits information over a uni-directional link.24. A computer program product as recited in claim 19, wherein thecomputer code for configuring the single line cable as an auxiliarychannel includes computer code for disabling a main link transmitter andenabling an auxiliary channel transceiver, wherein the auxiliary channeltransceiver transmits and/or receives side-band signals over abi-directional channel and wherein the main link transmitter transmitsinformation over a uni-directional link.
 25. The computer chip of claim21, further comprising an auxiliary channel transceiver and main linktransmitter, wherein the auxiliary channel transceiver transmits and/orreceives side-band signals over a bi-directional channel and wherein themain link transmitter transmits information over a uni-directional link.